Water-Assisted Concerted Layer Growth of Td‑Phase WTe2 for Nonlinear Hall Effect and Microwave Rectification

Abstract

The Td phase of tungsten ditelluride (WTe2), a noncentrosymmetric transition metal dichalcogenide, hosts rich correlated phenomena, topological states, and nonlinear transport responses. However, the scalable synthesis of high-quality few-layer WTe2 with precise layer control remains challenging. Here, we report a water-assisted chemical vapor deposition approach that deterministically grows monolayer to trilayer Td-WTe2 with controlled flake size and density. Moisture-mediated precursor liquefaction through salt-assisted intermediates enables vapor–liquid–solid growth and tunable layer numbers through a concerted layer growth mode. Transport studies reveal that trilayer WTe2 exhibits a nonlinear Hall effect susceptibility of 1.1 μm·V–1 at 10 K and 0.5 μm·V–1 at 50 K, nearly an order of magnitude higher than that in bilayers, consistent with the calculated Berry curvature dipole enhancement. Layer-dependent microwave rectification further highlights the influence of topological band structure and interlayer coupling. These results establish layer-engineered Td-WTe2 as a promising platform for nonlinear quantum transport and high-frequency optoelectronic applications.